The employment of glass melters in the formation of liquid glass from which glass fibers are produced is well known. Such furnaces generally contain a bed of hot glass which is maintained as a fluid by any suitable heating means. During the melting of the batch from which the liquid glass is formed, various hot gases are formed which are vented from the furnace. As a heat conservation measure, these gases have been vented from a crown at the rearward portion of the furnace and passed through a recuperator for recovery of heat. However, certain difficulties are encountered with present equipment. Previous installations of this type permit the inspiration of ambient air at the juncture of the melter crown and the recuperator. This inspiration dilutes the waste gases with the result that the temperature of the hot waste gases is reduced and heat recovery therefrom is resultingly reduced. Further, the reduction in the temperature of the waste heat gases causes condensation of volatile fluxes which drip onto the brickwork of the crown vent opening with the result that deterioration of the refractory occurs.